If your Video Exchange uploads with no sound, or the sound drops out as soon as you start playing, a recent Chrome change is the most likely cause.
On September 8, Chrome enabled a setting that automatically adjusts your microphone input level. It is tuned for speech, so it lowers the volume when it hears an instrument. This is affecting a lot of recording and livestreaming tools, not just ours.
Turn off the Chrome setting
Open a new tab in Chrome, type
chrome://flagsinto the address bar, and press Enter.In the search box at the top, search for Allow WebRTC to adjust the input volume.
Change the dropdown next to it from Default or Enabled to Disabled.
Click the Relaunch button at the bottom of the screen to apply the change.
If you use Microsoft Edge, the same setting is at edge://flags.
Before you submit
Play your recording back and confirm you can hear it before uploading. That catches most audio problems before they reach your teacher.
If you already submitted a silent video
You can delete a Video Exchange that has not received a response yet and upload a new file in its place. Deleting and reuploading resets your place in line for a reply from your teacher.
If your audio is still missing after turning the setting off, let us know what you are recording with and we will help you track it down.